Pentagramma triangularis occurs in rock crevices and at the base of overhanging boulders in drainages and on slopes and roadbanks. Occasional plants in which the farina is nearly absent may be encountered. These have been described as Pityrogramma triangularis var. viridis Hoover, a name of uncertain application that appears to refer to misshapen-spored hybrids of various parentage within the Pentagramma triangularis complex.